uryuu_ryuunosuke
A serial killer from Fate/Zero.
Though he is not a magus, he was selected by the Holy Grail to fulfill the war's requirement of seven Masters and seven Servants.
Ryuunosuke knows nothing about magic or the fourth Holy Grail War; his involvement in the war is simply to watch Caster kill people in unique and thrilling ways.
h4. See also
* Gilles de rais (caster) (fate)
* Type-Moon wiki (spoilers): http://typemoon.wikia.com/wiki/Uryuu_Ryuunosuke